A nail varnish applicator is known from European patent EP 0 651 955, comprising a rod, and bristles fixed in a housing of the rod, the housing being of oblong cross-section. In the examples shown in that patent, the opening of the housing has in cross-section a contour that matches the contour of the rod in the shape of a kidney or with two main sides slightly concave outwardly, such that the thickness of the wall surrounding the housing is constant.
A nail varnish applicator is also known from JP-4-28812, having a rod that includes a plurality of longitudinal grooves distributed in substantially uniform manner over its entire periphery.